The System Usability Scale (SUS) provides a “quick and dirty”, reliable tool for measuring the usability.   It consists of a 10 item questionnaire with five response options for respondents; from Strongly agree to Strongly disagree.  Originally created by John Brooke in 1986, it allows you to evaluate a wide variety of products and services, including hardware, software, mobile devices, websites and applications.

Benefits of using a SUS

SUS has become an industry standard, with references in over 1300 articles and publications.  The noted benefits of using SUS include that it:

• Is a very easy scale to administer to participants
• Can be used on small sample sizes with reliable results
• Is valid – it can effectively differentiate between usable and unusable systems

Considerations when using a SUS

If you are considering using a SUS, keep the following in mind:

• The scoring system is somewhat complex
• There is a temptation, when you look at the scores, since they are on a scale of 0-100, to interpret them as percentages, they are not
• The best way to interpret your results involves “normalizing” the scores to produce a percentile ranking
• SUS is not diagnostic - its use is in classifying the ease of use of the site, application or environment being tested

The System Usability Scale

When a SUS is used, participants are asked to score the following 10 items with one of five responses that range from Strongly Agree to Strongly disagree:

1. I think that I would like to use this system frequently.
2. I found the system unnecessarily complex.
3. I thought the system was easy to use.
4. I think that I would need the support of a technical person to be able to use this system.
5. I found the various functions in this system were well integrated.
6. I thought there was too much inconsistency in this system.